The present invention relates to a plasma display panel and a method for producing a plasma display panel. In particular, the present invention pertains to a plasma display panel characterized by the surface configurations of the electrodes on its front panel, and a method for producing a plasma display panel.
A plasma display panel (hereinafter referred to as PDP) has a structure comprising a front panel and a back panel arranged facing each other, which are sealed at their peripheral portions; and discharge gases such as neon (Ne), xenon (Xe) and the like are sealed in a discharge space defined between the front panel and the back panel.
The front panel is provided with a plurality of display electrodes each consisting of a scan electrode and a sustain electrode forming stripes, which are formed on one surface of a glass substrate, and a dielectric layer and a protective layer which cover these display electrodes. Each of the display electrodes comprises a transparent electrode and a bus electrode formed of a metal material on the transparent electrode.
The back panel is provided with a plurality of address electrodes forming the stripes which are formed on one surface of a glass substrate in a direction orthogonal to the display electrodes, a base dielectric layer which covers these address electrodes, striped partition walls which section the discharge space at every one of the address electrodes, and red, green and blue fluorescent layers formed in this order on each of the grooves defined by the partition walls.
The display electrodes and the address electrodes are orthogonal to each other so that their intersecting portions constitute discharge cells. These discharge cells are disposed in a matrix; and a pixel for color display is composed of three cells which have red, green and blue fluorescent layers, respectively, and which are disposed in the direction of the display electrodes. The PDP displays a colored image as follows: a predetermined voltage is sequentially applied between the scan electrodes and the address electrodes and between the scan electrodes and the sustain electrodes to cause a gas discharge, so that a UV caused by the gas discharge excites the fluorescent layers so as to emit light therefrom for the colored image.
When an aluminum (Al) electrode or a chromium (Cr)/copper (Cu)/chromium (Cr) electrode is used as the bus electrode, the electrode is formed by the steps of film-forming and patterning based on the semiconductor process. The bus electrode is therefore formed with high precision, but costs more since a vacuum apparatus is needed to form the film layer by the sputtering process. To solve this disadvantage, for example, bus electrodes of silver (Ag) are often formed of paste comprising silver (Ag) powder, by the printing method or the roll coating method which does not need a special vacuum apparatus.
The electrode paste using the silver (Ag) powder includes silver (Ag) powder as a solid component which is a conductive agent, glass frit for use in bonding, a resin such as a cellulose resin as a medium component, and a solvent such as a terpene-based solvent.
To improve the contrast of a screen, lately, there is provided a bus electrode which has a two-layered structure comprising a black layer (a layer in contact with a transparent layer) formed on the display side and a white layer formed on the black layer. The black layer is formed by applying a black electrode paste, and the white layer is formed by applying a conductive electrode paste on the black layer. In this case, as the black electrode paste, a resin composition comprising a black composite oxide of copper-iron (Cu—Fe), copper-chromium (Cu—Cr) or the like is used.
In concrete terms, the bus electrode is formed of these electrode pastes by applying each of the electrode pastes for each layer, and pattering each of the resulting layers (exposure and development), and calcining each of the resulting layers. To manufacture a PDP by a decreased number of steps, there are disclosed a method of collectively developing both layers which constitute a bus electrode having a two-layered structure and a black matrix; or a method of collectively exposing and developing a black layer and a white layer (cf. JP-A-2004-63247). The method disclosed in this patent document is expected to enable efficient formation of electrodes.